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[deliverable/binutils-gdb.git] / libdecnumber / decContext.c
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f5bc1778 1/* Decimal context module for the decNumber C Library.
168a2f77 2 Copyright (C) 2005, 2007, 2009 Free Software Foundation, Inc.
f5bc1778
DJ		 3 Contributed by IBM Corporation. Author Mike Cowlishaw.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
168a2f77 9 Software Foundation; either version 3, or (at your option) any later
f5bc1778
DJ		 10 version.
11
f5bc1778
DJ		 12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
168a2f77
DD		 17Under Section 7 of GPL version 3, you are granted additional
18permissions described in the GCC Runtime Library Exception, version
193.1, as published by the Free Software Foundation.
20
21You should have received a copy of the GNU General Public License and
22a copy of the GCC Runtime Library Exception along with this program;
23see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24<http://www.gnu.org/licenses/>. */
f5bc1778
DJ		 25
26/* ------------------------------------------------------------------ */
27/* Decimal Context module */
28/* ------------------------------------------------------------------ */
29/* This module comprises the routines for handling arithmetic */
30/* context structures. */
31/* ------------------------------------------------------------------ */
32
33#include <string.h> /* for strcmp */
34#include <stdio.h> /* for printf if DECCHECK */
5f5dfcbe 35#include "dconfig.h" /* for GCC definitions */
87d32bb7 36#include "decContext.h" /* context and base types */
f5bc1778
DJ		 37#include "decNumberLocal.h" /* decNumber local types, etc. */
38
f5bc1778
DJ		 39/* compile-time endian tester [assumes sizeof(Int)>1] */
40static const Int mfcone=1; /* constant 1 */
87d32bb7 41static const Flag *mfctop=(const Flag *)&mfcone; /* -> top byte */
f5bc1778 42#define LITEND *mfctop /* named flag; 1=little-endian */
f5bc1778
DJ		 43
44/* ------------------------------------------------------------------ */
45/* round-for-reround digits */
46/* ------------------------------------------------------------------ */
47const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
48
49/* ------------------------------------------------------------------ */
50/* Powers of ten (powers[n]==10**n, 0<=n<=9) */
51/* ------------------------------------------------------------------ */
52const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
53 10000000, 100000000, 1000000000};
54
55/* ------------------------------------------------------------------ */
56/* decContextClearStatus -- clear bits in current status */
57/* */
58/* context is the context structure to be queried */
59/* mask indicates the bits to be cleared (the status bit that */
87d32bb7 60/* corresponds to each 1 bit in the mask is cleared) */
f5bc1778
DJ		 61/* returns context */
62/* */
63/* No error is possible. */
64/* ------------------------------------------------------------------ */
65decContext *decContextClearStatus(decContext *context, uInt mask) {
66 context->status&=~mask;
67 return context;
68 } /* decContextClearStatus */
69
70/* ------------------------------------------------------------------ */
71/* decContextDefault -- initialize a context structure */
72/* */
73/* context is the structure to be initialized */
74/* kind selects the required set of default values, one of: */
75/* DEC_INIT_BASE -- select ANSI X3-274 defaults */
87d32bb7
DD		 76/* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
77/* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
78/* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
f5bc1778
DJ		 79/* For any other value a valid context is returned, but with */
80/* Invalid_operation set in the status field. */
81/* returns a context structure with the appropriate initial values. */
82/* ------------------------------------------------------------------ */
83decContext * decContextDefault(decContext *context, Int kind) {
84 /* set defaults... */
85 context->digits=9; /* 9 digits */
86 context->emax=DEC_MAX_EMAX; /* 9-digit exponents */
87 context->emin=DEC_MIN_EMIN; /* .. balanced */
88 context->round=DEC_ROUND_HALF_UP; /* 0.5 rises */
89 context->traps=DEC_Errors; /* all but informational */
90 context->status=0; /* cleared */
91 context->clamp=0; /* no clamping */
92 #if DECSUBSET
93 context->extended=0; /* cleared */
94 #endif
95 switch (kind) {
96 case DEC_INIT_BASE:
97 /* [use defaults] */
98 break;
99 case DEC_INIT_DECIMAL32:
100 context->digits=7; /* digits */
87d32bb7 101 context->emax=96; /* Emax */
f5bc1778
DJ		 102 context->emin=-95; /* Emin */
103 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
87d32bb7
DD		 104 context->traps=0; /* no traps set */
105 context->clamp=1; /* clamp exponents */
f5bc1778
DJ		 106 #if DECSUBSET
107 context->extended=1; /* set */
108 #endif
109 break;
110 case DEC_INIT_DECIMAL64:
111 context->digits=16; /* digits */
112 context->emax=384; /* Emax */
113 context->emin=-383; /* Emin */
114 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
87d32bb7
DD		 115 context->traps=0; /* no traps set */
116 context->clamp=1; /* clamp exponents */
f5bc1778
DJ		 117 #if DECSUBSET
118 context->extended=1; /* set */
119 #endif
120 break;
121 case DEC_INIT_DECIMAL128:
122 context->digits=34; /* digits */
123 context->emax=6144; /* Emax */
124 context->emin=-6143; /* Emin */
125 context->round=DEC_ROUND_HALF_EVEN; /* 0.5 to nearest even */
87d32bb7
DD		 126 context->traps=0; /* no traps set */
127 context->clamp=1; /* clamp exponents */
f5bc1778
DJ		 128 #if DECSUBSET
129 context->extended=1; /* set */
130 #endif
131 break;
132
133 default: /* invalid Kind */
134 /* use defaults, and .. */
135 decContextSetStatus(context, DEC_Invalid_operation); /* trap */
136 }
137
f5bc1778
DJ		 138 return context;} /* decContextDefault */
139
140/* ------------------------------------------------------------------ */
141/* decContextGetRounding -- return current rounding mode */
142/* */
143/* context is the context structure to be queried */
144/* returns the rounding mode */
145/* */
146/* No error is possible. */
147/* ------------------------------------------------------------------ */
148enum rounding decContextGetRounding(decContext *context) {
149 return context->round;
150 } /* decContextGetRounding */
151
152/* ------------------------------------------------------------------ */
87d32bb7 153/* decContextGetStatus -- return current status */
f5bc1778
DJ		 154/* */
155/* context is the context structure to be queried */
156/* returns status */
157/* */
158/* No error is possible. */
159/* ------------------------------------------------------------------ */
160uInt decContextGetStatus(decContext *context) {
161 return context->status;
162 } /* decContextGetStatus */
163
164/* ------------------------------------------------------------------ */
165/* decContextRestoreStatus -- restore bits in current status */
166/* */
167/* context is the context structure to be updated */
87d32bb7
DD		 168/* newstatus is the source for the bits to be restored */
169/* mask indicates the bits to be restored (the status bit that */
f5bc1778
DJ		 170/* corresponds to each 1 bit in the mask is set to the value of */
171/* the correspnding bit in newstatus) */
172/* returns context */
173/* */
174/* No error is possible. */
175/* ------------------------------------------------------------------ */
176decContext *decContextRestoreStatus(decContext *context,
177 uInt newstatus, uInt mask) {
178 context->status&=~mask; /* clear the selected bits */
179 context->status|=(mask&newstatus); /* or in the new bits */
180 return context;
181 } /* decContextRestoreStatus */
182
183/* ------------------------------------------------------------------ */
184/* decContextSaveStatus -- save bits in current status */
185/* */
186/* context is the context structure to be queried */
187/* mask indicates the bits to be saved (the status bits that */
188/* correspond to each 1 bit in the mask are saved) */
189/* returns the AND of the mask and the current status */
190/* */
191/* No error is possible. */
192/* ------------------------------------------------------------------ */
193uInt decContextSaveStatus(decContext *context, uInt mask) {
194 return context->status&mask;
195 } /* decContextSaveStatus */
196
197/* ------------------------------------------------------------------ */
198/* decContextSetRounding -- set current rounding mode */
199/* */
200/* context is the context structure to be updated */
201/* newround is the value which will replace the current mode */
202/* returns context */
203/* */
204/* No error is possible. */
205/* ------------------------------------------------------------------ */
206decContext *decContextSetRounding(decContext *context,
207 enum rounding newround) {
208 context->round=newround;
209 return context;
210 } /* decContextSetRounding */
211
212/* ------------------------------------------------------------------ */
213/* decContextSetStatus -- set status and raise trap if appropriate */
214/* */
215/* context is the context structure to be updated */
216/* status is the DEC_ exception code */
217/* returns the context structure */
218/* */
219/* Control may never return from this routine, if there is a signal */
220/* handler and it takes a long jump. */
221/* ------------------------------------------------------------------ */
222decContext * decContextSetStatus(decContext *context, uInt status) {
223 context->status|=status;
224 if (status & context->traps) raise(SIGFPE);
225 return context;} /* decContextSetStatus */
226
227/* ------------------------------------------------------------------ */
228/* decContextSetStatusFromString -- set status from a string + trap */
229/* */
230/* context is the context structure to be updated */
231/* string is a string exactly equal to one that might be returned */
232/* by decContextStatusToString */
233/* */
234/* The status bit corresponding to the string is set, and a trap */
235/* is raised if appropriate. */
236/* */
237/* returns the context structure, unless the string is equal to */
238/* DEC_Condition_MU or is not recognized. In these cases NULL is */
87d32bb7 239/* returned. */
f5bc1778
DJ		 240/* ------------------------------------------------------------------ */
241decContext * decContextSetStatusFromString(decContext *context,
242 const char *string) {
243 if (strcmp(string, DEC_Condition_CS)==0)
244 return decContextSetStatus(context, DEC_Conversion_syntax);
245 if (strcmp(string, DEC_Condition_DZ)==0)
246 return decContextSetStatus(context, DEC_Division_by_zero);
247 if (strcmp(string, DEC_Condition_DI)==0)
248 return decContextSetStatus(context, DEC_Division_impossible);
249 if (strcmp(string, DEC_Condition_DU)==0)
250 return decContextSetStatus(context, DEC_Division_undefined);
251 if (strcmp(string, DEC_Condition_IE)==0)
252 return decContextSetStatus(context, DEC_Inexact);
253 if (strcmp(string, DEC_Condition_IS)==0)
254 return decContextSetStatus(context, DEC_Insufficient_storage);
255 if (strcmp(string, DEC_Condition_IC)==0)
256 return decContextSetStatus(context, DEC_Invalid_context);
257 if (strcmp(string, DEC_Condition_IO)==0)
258 return decContextSetStatus(context, DEC_Invalid_operation);
259 #if DECSUBSET
260 if (strcmp(string, DEC_Condition_LD)==0)
261 return decContextSetStatus(context, DEC_Lost_digits);
262 #endif
263 if (strcmp(string, DEC_Condition_OV)==0)
264 return decContextSetStatus(context, DEC_Overflow);
265 if (strcmp(string, DEC_Condition_PA)==0)
266 return decContextSetStatus(context, DEC_Clamped);
267 if (strcmp(string, DEC_Condition_RO)==0)
268 return decContextSetStatus(context, DEC_Rounded);
269 if (strcmp(string, DEC_Condition_SU)==0)
270 return decContextSetStatus(context, DEC_Subnormal);
271 if (strcmp(string, DEC_Condition_UN)==0)
272 return decContextSetStatus(context, DEC_Underflow);
273 if (strcmp(string, DEC_Condition_ZE)==0)
274 return context;
275 return NULL; /* Multiple status, or unknown */
276 } /* decContextSetStatusFromString */
277
278/* ------------------------------------------------------------------ */
279/* decContextSetStatusFromStringQuiet -- set status from a string */
280/* */
281/* context is the context structure to be updated */
282/* string is a string exactly equal to one that might be returned */
283/* by decContextStatusToString */
284/* */
285/* The status bit corresponding to the string is set; no trap is */
286/* raised. */
287/* */
288/* returns the context structure, unless the string is equal to */
289/* DEC_Condition_MU or is not recognized. In these cases NULL is */
87d32bb7 290/* returned. */
f5bc1778
DJ		 291/* ------------------------------------------------------------------ */
292decContext * decContextSetStatusFromStringQuiet(decContext *context,
293 const char *string) {
294 if (strcmp(string, DEC_Condition_CS)==0)
295 return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
296 if (strcmp(string, DEC_Condition_DZ)==0)
297 return decContextSetStatusQuiet(context, DEC_Division_by_zero);
298 if (strcmp(string, DEC_Condition_DI)==0)
299 return decContextSetStatusQuiet(context, DEC_Division_impossible);
300 if (strcmp(string, DEC_Condition_DU)==0)
301 return decContextSetStatusQuiet(context, DEC_Division_undefined);
302 if (strcmp(string, DEC_Condition_IE)==0)
303 return decContextSetStatusQuiet(context, DEC_Inexact);
304 if (strcmp(string, DEC_Condition_IS)==0)
305 return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
306 if (strcmp(string, DEC_Condition_IC)==0)
307 return decContextSetStatusQuiet(context, DEC_Invalid_context);
308 if (strcmp(string, DEC_Condition_IO)==0)
309 return decContextSetStatusQuiet(context, DEC_Invalid_operation);
310 #if DECSUBSET
311 if (strcmp(string, DEC_Condition_LD)==0)
312 return decContextSetStatusQuiet(context, DEC_Lost_digits);
313 #endif
314 if (strcmp(string, DEC_Condition_OV)==0)
315 return decContextSetStatusQuiet(context, DEC_Overflow);
316 if (strcmp(string, DEC_Condition_PA)==0)
317 return decContextSetStatusQuiet(context, DEC_Clamped);
318 if (strcmp(string, DEC_Condition_RO)==0)
319 return decContextSetStatusQuiet(context, DEC_Rounded);
320 if (strcmp(string, DEC_Condition_SU)==0)
321 return decContextSetStatusQuiet(context, DEC_Subnormal);
322 if (strcmp(string, DEC_Condition_UN)==0)
323 return decContextSetStatusQuiet(context, DEC_Underflow);
324 if (strcmp(string, DEC_Condition_ZE)==0)
325 return context;
326 return NULL; /* Multiple status, or unknown */
327 } /* decContextSetStatusFromStringQuiet */
328
329/* ------------------------------------------------------------------ */
330/* decContextSetStatusQuiet -- set status without trap */
331/* */
332/* context is the context structure to be updated */
333/* status is the DEC_ exception code */
334/* returns the context structure */
335/* */
336/* No error is possible. */
337/* ------------------------------------------------------------------ */
338decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
339 context->status|=status;
340 return context;} /* decContextSetStatusQuiet */
341
342/* ------------------------------------------------------------------ */
87d32bb7 343/* decContextStatusToString -- convert status flags to a string */
f5bc1778
DJ		 344/* */
345/* context is a context with valid status field */
346/* */
87d32bb7 347/* returns a constant string describing the condition. If multiple */
f5bc1778
DJ		 348/* (or no) flags are set, a generic constant message is returned. */
349/* ------------------------------------------------------------------ */
350const char *decContextStatusToString(const decContext *context) {
351 Int status=context->status;
352
353 /* test the five IEEE first, as some of the others are ambiguous when */
354 /* DECEXTFLAG=0 */
355 if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
356 if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
357 if (status==DEC_Overflow ) return DEC_Condition_OV;
358 if (status==DEC_Underflow ) return DEC_Condition_UN;
359 if (status==DEC_Inexact ) return DEC_Condition_IE;
360
361 if (status==DEC_Division_impossible ) return DEC_Condition_DI;
362 if (status==DEC_Division_undefined ) return DEC_Condition_DU;
363 if (status==DEC_Rounded ) return DEC_Condition_RO;
364 if (status==DEC_Clamped ) return DEC_Condition_PA;
365 if (status==DEC_Subnormal ) return DEC_Condition_SU;
366 if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
367 if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
368 if (status==DEC_Invalid_context ) return DEC_Condition_IC;
369 #if DECSUBSET
370 if (status==DEC_Lost_digits ) return DEC_Condition_LD;
371 #endif
87d32bb7 372 if (status==0 ) return DEC_Condition_ZE;
f5bc1778
DJ		 373 return DEC_Condition_MU; /* Multiple errors */
374 } /* decContextStatusToString */
375
87d32bb7
DD		 376/* ------------------------------------------------------------------ */
377/* decContextTestEndian -- test whether DECLITEND is set correctly */
378/* */
379/* quiet is 1 to suppress message; 0 otherwise */
380/* returns 0 if DECLITEND is correct */
381/* 1 if DECLITEND is incorrect and should be 1 */
382/* -1 if DECLITEND is incorrect and should be 0 */
383/* */
384/* A message is displayed if the return value is not 0 and quiet==0. */
385/* */
386/* No error is possible. */
387/* ------------------------------------------------------------------ */
388Int decContextTestEndian(Flag quiet) {
389 Int res=0; /* optimist */
390 uInt dle=(uInt)DECLITEND; /* unsign */
391 if (dle>1) dle=1; /* ensure 0 or 1 */
392
393 if (LITEND!=DECLITEND) {
394 const char *adj;
395 if (!quiet) {
396 if (LITEND) adj="little";
397 else adj="big";
398 printf("Warning: DECLITEND is set to %d, but this computer appears to be %s-endian\n",
399 DECLITEND, adj);
400 }
401 res=(Int)LITEND-dle;
402 }
403 return res;
404 } /* decContextTestEndian */
405
f5bc1778
DJ		 406/* ------------------------------------------------------------------ */
407/* decContextTestSavedStatus -- test bits in saved status */
408/* */
409/* oldstatus is the status word to be tested */
410/* mask indicates the bits to be tested (the oldstatus bits that */
411/* correspond to each 1 bit in the mask are tested) */
412/* returns 1 if any of the tested bits are 1, or 0 otherwise */
413/* */
414/* No error is possible. */
415/* ------------------------------------------------------------------ */
416uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
417 return (oldstatus&mask)!=0;
418 } /* decContextTestSavedStatus */
419
420/* ------------------------------------------------------------------ */
421/* decContextTestStatus -- test bits in current status */
422/* */
423/* context is the context structure to be updated */
424/* mask indicates the bits to be tested (the status bits that */
425/* correspond to each 1 bit in the mask are tested) */
426/* returns 1 if any of the tested bits are 1, or 0 otherwise */
427/* */
428/* No error is possible. */
429/* ------------------------------------------------------------------ */
430uInt decContextTestStatus(decContext *context, uInt mask) {
431 return (context->status&mask)!=0;
432 } /* decContextTestStatus */
433
434/* ------------------------------------------------------------------ */
435/* decContextZeroStatus -- clear all status bits */
436/* */
437/* context is the context structure to be updated */
438/* returns context */
439/* */
440/* No error is possible. */
441/* ------------------------------------------------------------------ */
442decContext *decContextZeroStatus(decContext *context) {
443 context->status=0;
444 return context;
445 } /* decContextZeroStatus */
446
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